(Phys.org)—NASA's Chandra X-ray Observatory has helped astronomers to uncover a previously unidentified X-ray point source at the massive black hole in the center of a distant compact starburst galaxy known as Henize 2-10. ...

A revolutionary study involving researchers from the Max Planck Institute for Radioastronomy (MPIfR) in Germany, Trinity College Dublin in Ireland, and NASA in the USA, has obtained the sharpest ever images of one of the ...

Samsung Electronics said Friday that the discontinuation of the Galaxy Note 7 would cost the company about $3 billion during the current and next quarters, bringing the total cost of the recall to at least $5.3 billion.

Astronomers using data from the NASA/ESA Hubble Space Telescopes and other telescopes have performed an accurate census of the number of galaxies in the Universe. The group came to the surprising conclusion that there are ...

A joint team of University of Tokyo researchers and their collaborators, using ALMA and other telescopes that utilize radio waves for space observation, revealed that dense molecular gas disks a few hundred light years in ...

Samsung Electronics said Thursday it has expanded its recall of Galaxy Note 7 smartphones in the U.S. to include all replacement devices the company offered as a presumed safe alternative after the original Note 7s were found ...

The fiasco of Samsung's fire-prone Galaxy Note 7 smartphones—and Samsung's stumbling response to the problem—has left consumers from Shanghai to New York reconsidering how they feel about the South Korean tech giant and ...

Galaxy

A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The name is from the Greek root galaxias [γαλαξίας], meaning "milky," a reference to the Milky Way galaxy. Typical galaxies range from dwarfs with as few as ten million (107) stars up to giants with one trillion (1012) stars, all orbiting the galaxy's center of mass. Galaxies can also contain many multiple star systems, star clusters, and various interstellar clouds. The Sun is one of the stars in the Milky Way galaxy; the Solar System includes the Earth and all the other objects that orbit the Sun.

Historically, galaxies have been categorized according to their apparent shape (usually referred to as their visual morphology). A common form is the elliptical galaxy, which has an ellipse-shaped light profile. Spiral galaxies are disk-shaped assemblages with curving, dusty arms. Galaxies with irregular or unusual shapes are known as peculiar galaxies, and typically result from disruption by the gravitational pull of neighboring galaxies. Such interactions between nearby galaxies, which may ultimately result in galaxies merging, may induce episodes of significantly increased star formation, producing what is called a starburst galaxy. Small galaxies that lack a coherent structure could also be referred to as irregular galaxies.

There are probably more than 100 billion (1011) galaxies in the observable universe. Most galaxies are 1,000 to 100,000 parsecs in diameter and are usually separated by distances on the order of millions of parsecs (or megaparsecs). Intergalactic space (the space between galaxies) is filled with a tenuous gas of an average density less than one atom per cubic meter. The majority of galaxies are organized into a hierarchy of associations called clusters, which, in turn, can form larger groups called superclusters. These larger structures are generally arranged into sheets and filaments, which surround immense voids in the universe.

Although it is not yet well understood, dark matter appears to account for around 90% of the mass of most galaxies. Observational data suggests that supermassive black holes may exist at the center of many, if not all, galaxies. They are proposed to be the primary cause of active galactic nuclei found at the core of some galaxies. The Milky Way galaxy appears to harbor at least one such object within its nucleus.